Revert 148647 "Remove frame flattening support as Chromium has n..."

trunk/Source/core/platform/ScrollView.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 64 matching lines @@
 
 void ScrollView::removeChild(Widget* child)
 {
     ASSERT(child->parent() == this);
     child->setParent(0);
     m_children.remove(child);
 }
 
 void ScrollView::setHasHorizontalScrollbar(bool hasBar)
 {
-    ASSERT(!hasBar);
+    ASSERT(!hasBar || !avoidScrollbarCreation());
     if (hasBar && !m_horizontalScrollbar) {
         m_horizontalScrollbar = createScrollbar(HorizontalScrollbar);
         addChild(m_horizontalScrollbar.get());
         didAddHorizontalScrollbar(m_horizontalScrollbar.get());
         m_horizontalScrollbar->styleChanged();
     } else if (!hasBar && m_horizontalScrollbar) {
         willRemoveHorizontalScrollbar(m_horizontalScrollbar.get());
         removeChild(m_horizontalScrollbar.get());
         m_horizontalScrollbar = 0;
     }
-
+    
     if (AXObjectCache* cache = axObjectCache())
         cache->handleScrollbarUpdate(this);
 }
 
 void ScrollView::setHasVerticalScrollbar(bool hasBar)
 {
-    ASSERT(!hasBar);
+    ASSERT(!hasBar || !avoidScrollbarCreation());
     if (hasBar && !m_verticalScrollbar) {
         m_verticalScrollbar = createScrollbar(VerticalScrollbar);
         addChild(m_verticalScrollbar.get());
         didAddVerticalScrollbar(m_verticalScrollbar.get());
         m_verticalScrollbar->styleChanged();
     } else if (!hasBar && m_verticalScrollbar) {
         willRemoveVerticalScrollbar(m_verticalScrollbar.get());
         removeChild(m_verticalScrollbar.get());
         m_verticalScrollbar = 0;
     }
@@ skipping 304 matching lines @@
    
     ScrollbarMode hScroll = m_horizontalScrollbarMode;
     ScrollbarMode vScroll = m_verticalScrollbarMode;
 
     if (hScroll != ScrollbarAuto)
         newHasHorizontalScrollbar = (hScroll == ScrollbarAlwaysOn);
     if (vScroll != ScrollbarAuto)
         newHasVerticalScrollbar = (vScroll == ScrollbarAlwaysOn);
 
     if (m_scrollbarsSuppressed || (hScroll != ScrollbarAuto && vScroll != ScrollbarAuto)) {
-        if (hasHorizontalScrollbar != newHasHorizontalScrollbar && hasHorizontalScrollbar)
+        if (hasHorizontalScrollbar != newHasHorizontalScrollbar && (hasHorizontalScrollbar || !avoidScrollbarCreation()))
             setHasHorizontalScrollbar(newHasHorizontalScrollbar);
-        if (hasVerticalScrollbar != newHasVerticalScrollbar && hasVerticalScrollbar)
+        if (hasVerticalScrollbar != newHasVerticalScrollbar && (hasVerticalScrollbar || !avoidScrollbarCreation()))
             setHasVerticalScrollbar(newHasVerticalScrollbar);
     } else {
         bool sendContentResizedNotification = false;
-
+        
         IntSize docSize = totalContentsSize();
         IntSize fullVisibleSize = visibleContentRect(IncludeScrollbars).size();
 
         if (hScroll == ScrollbarAuto) {
             newHasHorizontalScrollbar = docSize.width() > visibleWidth();
             if (newHasHorizontalScrollbar && !m_updateScrollbarsPass && docSize.width() <= fullVisibleSize.width() && docSize.height() <= fullVisibleSize.height())
                 newHasHorizontalScrollbar = false;
         }
         if (vScroll == ScrollbarAuto) {
             newHasVerticalScrollbar = docSize.height() > visibleHeight();
             if (newHasVerticalScrollbar && !m_updateScrollbarsPass && docSize.width() <= fullVisibleSize.width() && docSize.height() <= fullVisibleSize.height())
                 newHasVerticalScrollbar = false;
         }
 
         // If we ever turn one scrollbar off, always turn the other one off too.  Never ever
         // try to both gain/lose a scrollbar in the same pass.
         if (!newHasHorizontalScrollbar && hasHorizontalScrollbar && vScroll != ScrollbarAlwaysOn)
             newHasVerticalScrollbar = false;
         if (!newHasVerticalScrollbar && hasVerticalScrollbar && hScroll != ScrollbarAlwaysOn)
             newHasHorizontalScrollbar = false;
 
         bool scrollbarIsOverlay = ScrollbarTheme::theme()->usesOverlayScrollbars();
-        if (hasHorizontalScrollbar != newHasHorizontalScrollbar && hasHorizontalScrollbar) {
+        if (hasHorizontalScrollbar != newHasHorizontalScrollbar && (hasHorizontalScrollbar || !avoidScrollbarCreation())) {
             if (!scrollbarIsOverlay)
                 sendContentResizedNotification = true;
             if (scrollOrigin().y() && !newHasHorizontalScrollbar && !scrollbarIsOverlay)
                 ScrollableArea::setScrollOrigin(IntPoint(scrollOrigin().x(), scrollOrigin().y() - m_horizontalScrollbar->height()));
             if (hasHorizontalScrollbar)
                 m_horizontalScrollbar->invalidate();
             setHasHorizontalScrollbar(newHasHorizontalScrollbar);
         }
 
-        if (hasVerticalScrollbar != newHasVerticalScrollbar && hasVerticalScrollbar) {
+        if (hasVerticalScrollbar != newHasVerticalScrollbar && (hasVerticalScrollbar || !avoidScrollbarCreation())) {
             if (!scrollbarIsOverlay)
                 sendContentResizedNotification = true;
             if (scrollOrigin().x() && !newHasVerticalScrollbar && !scrollbarIsOverlay)
                 ScrollableArea::setScrollOrigin(IntPoint(scrollOrigin().x() - m_verticalScrollbar->width(), scrollOrigin().y()));
             if (hasVerticalScrollbar)
                 m_verticalScrollbar->invalidate();
             setHasVerticalScrollbar(newHasVerticalScrollbar);
         }
 
         if (sendContentResizedNotification && m_updateScrollbarsPass < cMaxUpdateScrollbarsPass) {
@@ skipping 799 matching lines @@
 {
 }
 
 bool ScrollView::platformIsOffscreen() const
 {
     return false;
 }
 
 
 }